Method and system for trans-lamina spinal fixation

ABSTRACT

A method of providing spinal stabilization is provided herein. More specifically, the method includes positioning a plurality of fixation assemblies within a plurality of vertebrae in a trans-lamina orientation wherein each fixation assembly includes a proximal portion configured to securely receive a stabilization element (e.g., a stabilization rod). The proximal portions of the various fixation assemblies can be aligned so as to secure at least one stabilization element in a desired position (e.g., along and above a midline of the patient&#39;s spine, adjacent and parallel to the midline). A system for providing spinal stabilization is also provided which utilizes trans-lamina delivery and positioning of fixation assemblies within target vertebrae thereby providing stronger fixation and a significant reduction in associated tissue damage.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Ser. No. 13/793,431 filed onMar. 11, 2013, which is a continuation of U.S. Ser. No. 12/947,664 filedon Nov. 16, 2010 (now U.S. Pat. No. 8,414,624), which is a continuationof U.S. Ser. No. 12/035,684 filed on Feb. 22, 2008 (now U.S. Pat. No.7,857,835), the entire contents of each of which are incorporated byreference herein.

FIELD OF USE

The present disclosure relates to spinal fixation procedures, inparticular to methods and systems of securely positioning spinalfixation assemblies within vertebra(e).

BACKGROUND

Spinal fixation procedures are utilized to align and/or fix desiredrelationships between adjacent vertebral bodies. Such procedurestypically include positioning a plurality of spinal fixation assemblieswithin target vertebrae. These assemblies usually include a threadedshank portion configured to be disposed (e.g., threaded) within avertebra and a proximal receiving head configured to receive and securesome type of spinal stabilization element (e.g., a rigid rod, a cable, abiological construct, etc.). Once these assemblies are disposed withinthe desired vertebrae, the spinal stabilization rod can be positionedand secured within the receiving heads thereby allowing the rod toextend along a length of the patient's spinal column. Once secured assuch, the installed spinal stabilization rod can hold the vertebrae inthe desired spatial relationship, either until desired healing or spinalfusion has taken place, or for some longer period of time.

Due to the intricacies of working in the proximity of the spinal column,such procedures can result in serious patient injury and/or insignificant patient trauma. For example, such procedures typicallyrequire the spinal fixation assemblies to be delivered directly (i.e.,substantially perpendicular to the midline of the patient's spinalcolumn) into a lateral mass of a target vertebra. In light of thistrajectory, significant amounts of muscle and tissue must be strippedfrom the treatment site due to the relatively large distance between thelateral mass entry point and the midline of the spinal column. Also, anyslight miscalculation in the delivery trajectory can result inpenetration of a distal portion of the assembly (e.g., a pointed tip)into the spinal canal thereby causing significant patient injury. As afurther disadvantage, the limited bone mass and/or bone densitytypically found in the lateral mass portion of a vertebra significantlylimits the amount of area available for contacting the fixation assemblythereby hindering the ability to effectively position the fixationassembly within the vertebra.

Thus, there remains a need for methods and systems capable of securelypositioning fixation assemblies within target vertebrae while alsominimizing the risk of injury and associated patient trauma.

SUMMARY

Methods and systems for effectively positioning spinal fixationassemblies within target vertebrae while also reducing any associatedpatient trauma (e.g., muscle stripping, tissue damage, etc.) areprovided herein. More specifically, the presently disclosed embodimentsutilize trans-lamina delivery and positioning of fixation assemblieswithin target vertebrae. As described below, trans-lamina deliveryprovides numerous advantages relative to traditional direct deliverytechniques. For example, trans-lamina delivery significantly increasesthe surface area of vertebral bone available to contact the fixationassembly thereby allowing for the use of larger (e.g., longer and/orwider) fixation assemblies which can enable a stronger, more securefixation. Additionally, trans-lamina delivery and positioning of thefixation assembly within the vertebra allows each fixation assembly toenter the vertebra at a location significantly closer to a midline of apatient's spinal column as opposed to traditional direct deliverytechniques thereby resulting in significantly less tissue and/or muscledamage. Also, the trans-lamina trajectory reduces the risk of injuryresulting from penetration of the assembly into the spinal canalbecause, in contrast to traditional direct delivery techniques theassembly can be angled away from the patient's spinal column duringdelivery rather than being delivered along a substantially perpendiculartrajectory.

Various aspects of a method of providing spinal stabilization aredisclosed herein. In one such aspect, the method includes positioning afirst fixation assembly within a first vertebra in a trans-laminaorientation and positioning a second fixation assembly within a secondvertebra in a trans-lamina orientation such that a proximal receivinghead of the first fixation assembly is aligned with a proximal receivinghead of the second fixation assembly. Next, the method can includepositioning a spinal stabilization element within the proximal receivingheads of both the first and second fixation assemblies and securing thestabilization element (e.g., rod) within each of the proximal receivingheads.

The fixation assemblies can be positioned within any number and/or type(e.g., cervical, thoracic, lumbar) of vertebra as required by any givenprocedure. Also, the method can include positioning the fixationassemblies in various manners so as to optimize the orientation of thestabilization element (e.g., stabilization rod) relative to thepatient's spinal column. For example, in one such embodiment, theproximal receiving heads of the various fixation assemblies can bepositioned along and over the midline of a patient's spinal column suchthat a single stabilization element can be coupled thereto which allowsthe stabilization element to be positioned along and over the midline ofthe patient's spinal column. In other embodiments, the proximalreceiving heads of each of a first plurality of fixation assemblies canbe positioned along one side of the midline of a patient's spinalcolumn, and the proximal receiving heads of each of a second pluralityof fixation assemblies can be positioned on the opposite side of themidline of the patient's spinal column. In such an embodiment, a firststabilization element can be coupled to the receiving heads of each ofthe first plurality of fixation assemblies, and a second stabilizationelement can be coupled to the proximal receiving heads of each of thesecond plurality of fixation assemblies thereby positioning thestabilization elements on opposite sides of the midline of the patient'sspinal column. Thus, such trans-lamina delivery and positioning of thefixation assemblies allow for increased stability as well as versatilityin positioning of the stabilization element(s) relative to the patient'sspinal column.

The method can also include various procedures for further optimizingthe delivery and positioning of the fixation assemblies within thevertebrae. For example, the method can include removing various portionsof at least one (or all) target vertebra prior to engagement of thefixation assembly. Such truncation can be utilized to better positionthe proximal end(s) of the fixation assembl(ies) relative to astabilization element and/or to facilitate engagement of the fixationassembl(ies) to the vertebra(e) by providing access to an optimalportion of the vertebral bone. For example, the method can includeremoval or truncation of the spinous process of the vertebra(e) therebyallowing for positioning of the proximal end(s) of the assembl(ies)along the midline of the patient's spinal column.

The spinal fixation assembl(ies) can be configured in various manners.In general, the assemblies can include any type of assembly configuredto securely engage a vertebra, and also having a proximal portionconfigured to securely receive a stabilization element. For example, thefixation assembly can include a bone anchor element (e.g., a bone screw)having a proximal end which is coupled to a receiving head configured toreceive and secure a stabilization element thereto. In an exemplaryembodiment, the receiving head is movably coupled to the bone anchorelement. For example, the receiving head can be capable of polyaxialmotion relative to the bone anchor. Additionally, the receiving head canbe configured in virtually any manner capable of receiving and securingthe stabilization element. In an exemplary embodiment, the receivinghead can include a “U-shaped” opening configured to receive thestabilization element. In such an embodiment, the U-shaped opening ofthe receiving head can include various internal threads (or otherengagement means) configured to receive any type of closure mechanism(e.g., a set screw) having a corresponding set of threads therebysecuring the stabilization element to the assembly.

In another aspect, a method of providing spinal stabilization isprovided which includes positioning a plurality of fixation assemblieswithin a plurality of vertebrae wherein the fixation assemblies arepositioned within the vertebrae in a trans-lamina orientation. In anexemplary embodiment, each fixation assembly can include a threadedshank with a proximal end polyaxially coupled to a receiving head. Next,the method can include securing a first stabilization element within thereceiving head of a first fixation assembly and also within a receivinghead of a second fixation assembly thereby positioning the stabilizationelement adjacent a midline of a patient's spinal column. Optionally, themethod can also include securing a second stabilization element within areceiving head of a third fixation assembly and also within a receivinghead of a fourth fixation assembly thereby positioning the secondstabilization element adjacent a midline of a patient's spinal columnand on an opposite side of the midline as compared to the firststabilization element.

Various aspects of a system of providing spinal stabilization are alsodisclosed herein. In one such aspect, the system includes a plurality offixation assemblies secured to a plurality of vertebrae in atrans-lamina orientation wherein each fixation assembly includes a boneanchor element movably coupled to a receiving head. The system furtherincludes a stabilization element (e.g., a rod, cable, etc.) capable ofbeing secured within a plurality of such receiving heads such that thestabilization element can be positioned in a substantially parallelorientation relative to a midline of a patient's spine. Like above, thestabilization element(s) can be positioned at various locations relativeto the patient's spinal column. For example, the system can include astabilization element positioned along and above the midline of thepatient's spine. In other embodiments, the system can include astabilization element(s) positioned adjacent the midline of thepatient's spine. For example, the system can include first and secondspinal stabilization elements positioned on opposite sides of themidline of a patient's spinal column.

These and other aspects of the presently disclosed methods and systemsare detailed below.

BRIEF DESCRIPTION OF THE DRAWINGS

The presently disclosed embodiments will be more fully understood fromthe following detailed description taken in conjunction with theaccompanying drawings, in which:

FIG. 1A is a perspective view of a prior art procedure wherein afixation assembly is delivered directly into a lateral mass of a targetvertebra;

FIG. 1B is another view of the direct delivery technique illustrated inFIG. 1A;

FIG. 2 is a representation showing a fixation assembly positioned withina target vertebra in a trans-lamina orientation;

FIG. 3A is a view of an embodiment wherein a plurality of fixationassemblies are positioned within vertebrae in a trans-laminaorientation;

FIG. 3B is a view of another embodiment wherein a plurality of fixationassemblies are positioned within vertebrae in a trans-laminaorientation;

FIG. 4A is a perspective view of an embodiment wherein a spinalstabilization element is positioned along and above a midline of apatient's spinal column;

FIG. 4B is a side view of the embodiment of FIG. 4A; and

FIG. 5 is a view of an embodiment wherein portions of a vertebra havebeen truncated prior to trans-lamina delivery and positioning of thefixation assembly.

DETAILED DESCRIPTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the system and method disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those skilled in the art will understand that the system andmethod described herein and illustrated in the accompanying drawings arenon-limiting exemplary embodiments and that the scope of the presentdisclosure is defined solely by the claims. The features illustrated ordescribed in connection with one exemplary embodiment may be combinedwith the features of other embodiments. Such modifications andvariations are intended to be included within the scope of the presentdisclosure.

Methods and systems for spinal stabilization utilizing trans-laminadelivery and positioning of fixation assemblies within target vertebraeare provided herein. In contrast to traditional direct delivery offixation assemblies into the lateral mass, trans-lamina deliveryincreases the amount of vertebral bone available to receive the fixationassembly thereby providing for a stronger fixation and improvedtherapeutic results. Also, the larger amount of vertebral bone availableenables the use of larger (e.g., longer and/or wider) fixationassemblies which also facilitates a stronger fixation. Trans-laminadelivery and positioning of the fixation assemblies also significantlyreduces the amount of tissue and/or muscle damage resulting from theprocedure because the fixation assembly can enter the target vertebra ata location closer to the midline of a patient's spinal column ascompared to traditional direct delivery procedures. As a furtheradvantage, the delivery trajectory made available by such trans-laminadelivery and positioning reduces the potential for inadvertent damage tothe spine and/or surrounding areas because the assemblies can be angledaway from the patient's spinal canal during delivery.

FIGS. 1A and 1B illustrate a traditional spinal fixation techniquewherein a fixation assembly 10 is directly delivered to and positionedwithin the lateral mass (L.M.) of a target vertebra V₁. As shown, directdelivery of the fixation assembly 10 to the lateral mass (L.M.)significantly limits the usable entry points (E) for the fixationassembly 10 because the user must ensure against penetration of thefixation assembly 10 into the spinal canal (S.C.) and/or surroundingnerves. As shown, any slight miscalculation in delivery trajectory canresult in unwanted introduction of the distal end 10 _(D) of theassembly 10 into the spinal canal (S.C.). Additionally, the traditionalapproach typically results in significant tissue damage because thefixation assembly 10 must be delivered to the vertebra V₁ at an entrypoint (E) which is a relatively large distance (D₁) away from themidline (M.L.) of the patient's spinal column. Thus, to provide accessto the entry point (E), the procedure requires significant amounts ofmuscle and/or tissue stripping. As a further drawback, in light of therelatively small amount of vertebral bone present in the lateral mass(L.M.), the procedure is typically limited to fixation assemblies havinga relatively short length (L₁) thereby hindering the ability to providea strong fixation between assembly 10 and the target vertebra V₁.

In contrast, FIG. 2 shows an exemplary embodiment of the presentlydisclosed method wherein a spinal fixation assembly 10 is delivered andpositioned within a target vertebra V₁ in a trans-lamina orientation.That is, the fixation assembly 10 is delivered across a lamina portionof the vertebra V₁ and into the lateral mass (L.M.). As will bedescribed, such a trajectory can allow at least a portion of thefixation assembly 10 to be positioned above the midline (M.L.) of thepatient's spinal column (S.C.). For example, in those procedures whichrequire positioning a stabilization rod offset from the midline (M.L.)of the spinal column (as shown in FIGS. 2 and 3A), the fixation assemblycan be delivered and positioned within the vertebra V₁ in a trans-laminaorientation such that a threaded shank 12 of the fixation assembly 10crosses over the midline (M.L.) of the spinal column (S.C.). Similarly,in those procedures requiring the placement of a stabilization rod alongand above the midline (as shown in FIGS. 4A-4B), trans-lamina deliverycan allow for a proximal receiving head of the fixation assembly 10 tobe positioned substantially over the midline (as shown in FIG. 5).

The presently disclosed trans-lamina fixation procedures providenumerous benefits over the above-described direct delivery approach. Forinstance, such trans-lamina delivery and positioning allows for astronger fixation between the fixation assembly 10 and correspondingvertebral bone V₁ because a larger surface area and/or denser bone masscan be utilized to receive and engage the fixation assembly 10. In lightof the enlarged surface area, the fixation assembly 10 can include alarger (e.g., longer and/or wider) bone anchor element 12 which alsocontributes to a stronger fixation. Additionally, trans-lamina deliveryand positioning significantly reduces the risk of injury because thedistal end of the fixation assembly 10 _(D) can be angled away from thespinal canal (S.C.) during delivery as opposed to the prior arttrajectory which is substantially perpendicular to the the spinal column(S.C.). Additionally, in utilizing trans-lamina delivery andpositioning, the assembly 10 can enter the vertebrae V₁ at atrans-lamina entry point (E′) which is a substantially shorter distance(D₂) from the midline (M.L.) of the spinal column as compared to thedistance (D₁, shown in FIG. 1A) required when utilizing the traditionaldirect delivery approach. Thus, the presently disclosed trans-laminadelivery and positioning of fixation assemblies 10 within vertebrae V₁significantly reduces any associated tissue and/or muscle damage ascompared to the traditional approach.

As will be appreciated by those skilled in the art, the fixationassembly 10 can be virtually any type of assembly having a distalportion 12 configured to engage vertebral bone V₁ and having a proximalportion 14 configured to securely receive some type of spinalstabilization element (e.g., a stabilization rod). For example,referring again to FIG. 2, the fixation assembly 10 can include a boneanchor element 12 configured to securely engage vertebral bone V₁. Aswill be appreciated by those skilled in the art, the bone anchor element12 can be any type of element configured to engage vertebral bone. In anexemplary embodiment, the bone anchor element 12 is a bone screw 12having a thread extending along a portion of the screw 12 therebyallowing the element 12 to be effectively delivered to and securelypositioned within the vertebra V₁. While the bone anchor element 12 caninclude a wide range of sizes and/or shapes, as indicated above, anadvantage of trans-lamina delivery is the ability to utilize largerelements 12 as compared to the traditional approach. For example, FIG. 2shows an embodiment of a bone anchor element 12 having a length (L₂)substantially longer than the length (L₁) of the bone screw utilized inthe traditional technique depicted in FIG. 1B.

Again referring to FIG. 2, the proximal portion 14 of the fixationassembly 10 can be configured in various manners to securely engage aspinal stabilization element (e.g., a stabilization rod). For example,the fixation assembly 10 can include a receiving head 14 coupled to aproximal end of the bone anchor element 12p. Such a receiving head 14can be configured to securely receive the spinal stabilization elementin various manners. For example, in an exemplary embodiment, thereceiving head 14 can include a “U”-shaped opening 16 configured toreceive the stabilization element. In other embodiments, the opening 16can include various other shapes capable of receiving the stabilizationelement. The receiving head 14 can also be configured in various mannersso as to secure the stabilization element therein. For example, thereceiving head 14 can include various internal threads (not shown)capable of receiving a closure mechanism 13 (see FIG. 3A) therebysecuring the stabilization element within the head 14. Those skilled inthe art will appreciate that the receiving head 14 can be configured invarious manners so as to retain the stabilization element therein.

The fixation assembly 10 can also be configured to allow for movement ofthe receiving head 14 relative to the bone anchor element 12. While thereceiving head 14 can be coupled to the bone anchor element 12 in anynumber of manners to provide any desired movement and/or range ofmotion, in an exemplary embodiment, the head 14 is capable of polyaxialmovement relative to the element 12. Those skilled in the art willappreciate that the receiving head 14 and/or the proximal end 12 _(P) ofthe bone anchor element 12 can be configured and/or coupled in varioussuch manners so as to provide such polyaxial motion. In otherembodiments, the fixation assembly 10 can be configured so as to allowthe receiving head 14 to be rotated relative to the bone-engagingelement 12 thereby allowing for the openings 16 of the various receivingheads 14 to be aligned relative to one another prior to delivery of thestabilization element.

As shown in FIGS. 3A-4B, following trans-lamina positioning of thevarious fixation assemblies 10, one or more stabilization elements(e.g., stabilization rods) can be secured thereto to provide the desiredtherapeutic effect. As will be apparent to those skilled in the art, thestabilization element 20 can be a rod, a cable, a biological construct,etc. Further, the stabilization element 20 can have a wide range ofdimensions (e.g., length and/or diameter) and/or shapes (e.g., straight,contoured, etc.) which are selected in accordance with the patient'sanatomy and/or the requirements of the surgical procedure. As alsoshown, the method can include positioning first and second stabilizationelements on opposite sides of the midline (M.L.) of the patient's spinalcolumn (as shown in FIGS. 3A-3B) or the method can include positioning asingle stabilization element along and above the midline (M.L.) of apatient's spinal column (as shown in FIGS. 4A-4B). These procedures arenow discussed in greater detail.

FIGS. 3A and 3B show an exemplary embodiment which includes a pluralityof fixation assemblies 10′, 10″, 10′″, 11′, 11″, 11′″ being deliveredand positioned within target vertebrae in a trans-lamina orientation.Those skilled in the art will appreciate that these assemblies 10′, 10″,10′″, 11′, 11″, 11′″ can be delivered to any pattern of vertebrae V₁,V₂, V_(n) (e.g., every vertebrae, every other vertebrae, every fourthvertebrae, etc). For example, referring to FIG. 3A, the method caninclude engaging a first plurality of fixation assemblies 10′, 10″, 10′″to a plurality of vertebrae V₁, V₃, V₅ in a trans-lamina orientationsuch that the proximal portions of these assemblies 10′, 10″, 10′″ aredisposed adjacent a midline (M.L.) of the patient's spinal column. Themethod can further include delivering a second plurality of fixationassemblies 11′, 11″, 11′″ to a plurality of vertebrae V₂, V₄, V₆ in atrans-lamina orientation such that the proximal portions of thesefixation assemblies 11′, 11″, 11′″ are disposed adjacent the midline(M.L.) of the patient's spinal column and also on the opposite side ofthe midline (M.L.) as compared to first plurality of fixation assemblies10′, 10″, 10′″. Once positioned as such, a first stabilization element20 can be positioned and secured within the proximal ends of the firstplurality of fixation assemblies 10′, 10″, 10′″, and a secondstabilization element 20′ can be positioned and secured within theproximal ends of the second plurality of fixation assemblies 11′, 11″,11′″. Thus, as shown in FIG. 3A, the embodiment provides first andsecond stabilization elements 20, 20′ positioned on opposite sides ofthe midline (M.L.) of the patient's spine wherein the stabilizationelements 20, 20′ are substantially parallel to the midline (M.L.) of thespine. In other embodiments, the method can include positioning only oneplurality of fixation assemblies 10′, 10″, 10′″ along a single side ofthe midline (M.L.) of the patient's spine.

As indicated above, the presently disclosed method allows for deliveryand positioning of any number of fixation assemblies 10 to any numberand/or pattern of vertebrae V₁. For example, as shown in FIG. 3A, thefirst plurality of fixation assemblies 10′, 10″, 10′″ can be positionedin a trans-lamina orientation within every other vertebra V₁, V₃, V₅.Additionally, the second plurality of fixation assemblies 11′, 11″, 11′″can also be positioned within every other vertebra V₂, V₄, V₆ andstaggered with respect to the first plurality of fixation assembliessuch that each of the six fixation assemblies 10′, 10″, 10′″, 11′, 11″,11′″ are positioned within a distinct vertebra V₁-V₆. In otherembodiments, the method can include any number of fixation assemblies(e.g., 2, 3, 4, 5, 6, etc.) configured to receive and secure astabilization element 20 of any desired length. Additionally, as shownin FIG. 3B, the method can include delivering at least one fixationassembly of the first plurality of fixation assemblies 10′ and at leastone fixation assembly of the second plurality of fixation assemblies 11′to the same vertebra V₁ along trans-lamina trajectories. Additionally,the fixation assemblies of the first and/or second plurality of fixationassemblies 10′, 10″, 10′″, 11′, 11″, 11′″ can be secured to sequentialvertebra, every other vertebra, every fourth vertebra, or any otherpattern required and/or preferred for a given procedure. Suchversatility allows the surgeon to select optimal vertebral locations fordelivery and positioning of the fixation assemblies and stabilizationelements.

In other exemplary embodiments, the method can include the use of asingle stabilization element 20 positioned along and above the midline(M.L.) of a patient's spine. FIGS. 4A and 4B provide an example of suchan embodiment wherein a plurality (e.g., four) of fixation assemblies10, 10′, 10″, 10′″ are delivered in a trans-lamina orientation relativeto successive vertebra V₁, V₂, V₃, V₄ such that the proximal portions ofeach assembly 10, 10′, 10″, 10′″ are substantially aligned along andabove the midline (M.L.) of the patient's spine. Like above, thefixation assemblies 10, 10′, 10″, 10′″ can be delivered to the vertebraein various patterns and/or configurations so as to position the proximalportions of the assemblies in the desired location. For example, asshown in FIGS. 4A and 4B, the fixation assemblies 10, 10′, 10″, 10′″ canbe delivered such that each bone anchor is angled in a directionopposite of its adjacent bone anchor along successive vertebrae V₁, V₂,V₃, V₄. In other embodiments, similar to what is described above, thefixation assemblies 10, 10′, 10″, 10′″ can be delivered to every othervertebra, every fourth vertebra, etc. Also, any number of fixationassemblies 10, 10′, 10″, etc. can be utilized depending on the patient'sanatomy and/or requirements of the procedure. For example, the methodcan utilize 2, 3, 4, 5, or more fixation assemblies 10. In short, themethod can include any number of fixation assemblies positioned withinany number and/or pattern of target vertebrae in a trans-laminaorientation so as to securely position at least one stabilizationelement in a desired location.

Various embodiments of the method can also include modifying and/ortruncating various portions of the target vertebrae V₁ so as to furtheroptimize the procedure. More specifically, removing various portions ofthe target vertebra(e) V₁ can provide access to an optimal entry pointof the vertebral bone and can facilitate positioning of the proximal endof the fixation assemblies 10 at desired locations. For example, FIGS.4A, 4B and 5 provide an exemplary embodiment wherein portions of variousvertebrae (V₁-V₄ in FIGS. 4A-4B and V₁ in FIG. 5) have been removed ortruncated thereby allowing the proximal portion of each fixationassembly 10 to be positioned above and along the midline (M.L.) of thepatient's spine. Additionally, removing these portions of the targetvertebrae V₁ can provide an easier target for delivery of the fixationassemblies 10 because the truncated vertebrae V₁ can be substantiallyplanar and therefore easier to engage the assemblies 10 thereto. As willbe apparent to those skilled in the art, the method can include removingany portion of the vertebra(e) V₁ as required by a given procedure. Asshown in the exemplary embodiments of FIGS. 4A, 4B, and 5, the methodcan also include removing (or truncating) the spinous process of all (orat least one) vertebrae V₁.

Various embodiments of a system of providing spinal stabilization arealso disclosed herein. In an exemplary embodiment, the system caninclude a plurality of fixation assemblies 10, 10′, 10″, etc. engaged toa plurality of vertebrae V₁, V₂, V₃, etc. in a trans-lamina orientationwherein each fixation assembly 10 includes a bone anchor element (e.g.,a bone screw) 12 coupled to a movable receiving head 14. The system canfurther include a stabilization element (e.g., a rod, cable, etc.) 20secured within a plurality of such movable heads 14 such that thestabilization element 20 maintains a substantially parallel orientationrelative to a midline (M.L.) of a patient's spine. Like above, thestabilization element(s) 10 can be positioned at various locationsrelative to the patient's spinal column (S.C.). For example, the systemcan include a stabilization element 20 positioned along and above themidline (M.L.) of the patient's spine. In other embodiments, the systemcan include a stabilization element(s) 20 positioned adjacent themidline (M.L.) of the patient's spine. For example, the system caninclude first and second spinal stabilization elements 20, 20′positioned on opposite sides of the midline (M.L.) of a patient's spinalcolumn.

One skilled in the art will appreciate further features and advantagesof the presently disclosed method and system based on theabove-described embodiments. Accordingly, the present disclosure is notto be limited by what has been particularly shown and described, exceptas indicated by the appended claims. All publications and referencescited herein are expressly incorporated herein by reference in theirentirety.

What is claimed is:
 1. A method of providing spinal stabilization,comprising: positioning a first fixation assembly within a firstvertebra in a trans-lamina orientation; positioning a second fixationassembly within a second vertebra in a trans-lamina orientation suchthat a proximal receiving head of the first fixation assembly is alignedwith a proximal receiving head of the second fixation assembly;positioning a spinal stabilization element within the proximal receivingheads of both the first and second fixation assemblies; and securing thespinal stabilization element within each of the proximal receivingheads.
 2. The method of claim 1, wherein the proximal receiving head ofeach fixation assembly is positioned along and above a midline of apatient's spinal column.
 3. The method of claim 1, wherein the proximalreceiving head of each fixation assembly is positioned adjacent amid-line of a patient's spinal column.
 4. The method of claim 1, furthercomprising: removing a portion of at least one vertebra; and positioningthe fixation assembly within the at least one vertebra in a trans-laminaorientation.
 5. The method of claim 4, wherein the spinous process ofthe vertebra is removed.
 6. The method of claim 5, wherein the proximalreceiving head of each fixation assembly is positioned along and above amidline of a patient's spinal column.
 7. The method of claim 1, whereinthe fixation assemblies are positioned within adjacent vertebrae.
 8. Themethod of claim 1, wherein the fixation assemblies are positioned withinnon-adjacent vertebrae.
 9. The method of claim 1, wherein each receivinghead is configured for polyaxial motion.
 10. The method of claim 1,wherein each receiving head include a U-shaped opening configured tosecurely receive a stabilization element.
 11. A method for providingspinal stabilization, comprising: positioning a plurality of fixationassemblies within a plurality of vertebrae, the fixation assembliesbeing positioned within the vertebrae in a trans-lamina orientation,each fixation assembly having a threaded shank with a proximal endpolyaxially coupled to a receiving head; and securing a firststabilization element within the receiving head of a first fixationassembly and a receiving head of a second fixation assembly therebypositioning the stabilization element adjacent a midline of a patient'sspinal column.
 12. The method of claim 11, further comprising: securinga second stabilization element within a receiving head of a thirdfixation assembly and a receiving head of a fourth fixation assemblythereby positioning the second stabilization element adjacent a midlineof a patient's spinal column and on an opposite side of the midline ascompared to the first stabilization element.
 13. The method of claim 11,wherein the first and second stabilization elements are stabilizationrods.
 14. The method of claim 11, wherein at least one of the pluralityof vertebrae is a cervical vertebra.
 15. The method of claim 11, whereinthe stabilization element extends along at least three vertebrae.
 16. Asystem for providing spinal stabilization, comprising: a plurality offixation assemblies, each fixation assembly configured to be implantedwithin a vertebra in a trans-lamina orientation, each fixation assemblyhaving a bone-engaging element coupled to a movable receiving head; anda stabilization element secured within each movable receiving head suchthat the stabilization element maintains a substantially parallelorientation relative to a midline of a patient's spine.
 17. The systemof claim 16, wherein the stabilization element is configured to bepositioned along and above the midline of the patient's spine.
 18. Thesystem of claim 16, wherein the stabilization element is configured tobe positioned adjacent the midline of the patient's spine.
 19. Thesystem of claim 18, further comprising: a second stabilization elementsecured within a second plurality of movable receiving heads such thatthe second fixation assembly is configured to be positioned adjacent themidline of the patient's spine and on the opposite side of the midlinerelative to the first spinal stabilization element.
 20. The system ofclaim 16, wherein the stabilization element is a rod.